[PATCH 1 of 5 V3] clone: move file stream walk to a separate function

[Durham Goode]

# HG changeset patch
# User Durham Goode <durham at fb.com>
# Date 1367429921 25200
#      Wed May 01 10:38:41 2013 -0700
# Node ID 517845b6057f5f64c3085e29a33f7da8a3c84774
# Parent  a718a0ba6787ae9546d0aa453c8a7dae25d4405b
clone: move file stream walk to a separate function

Moves the file walk out of the stream method so that extensions can override it.

This allows an extension to decide what files should be streamed, and in
particular allows a stream without filelogs.

diff --git a/mercurial/wireproto.py b/mercurial/wireproto.py
--- a/mercurial/wireproto.py
+++ b/mercurial/wireproto.py
@@ -523,6 +523,10 @@
 def _allowstream(ui):
     return ui.configbool('server', 'uncompressed', True, untrusted=True)
 
+def _walkstreamfiles(repo):
+    # this is it's own function so extensions can override it
+    return repo.store.walk()
+
 def stream(repo, proto):
     '''If the server supports streaming clone, it advertises the "stream"
     capability with a value representing the version and flags of the repo
@@ -544,7 +548,7 @@
         lock = repo.lock()
         try:
             repo.ui.debug('scanning\n')
-            for name, ename, size in repo.store.walk():
+            for name, ename, size in _walkstreamfiles(repo):
                 if size:
                     entries.append((name, size))
                     total_bytes += size